1. Field of the Invention
This invention relates to and has among its objects novel blood-coagulation promoting products and methods of preparing them. It is a particular object of the invention to provide blood-coagulation-promoting products that contain substantial amounts of Factor VIII Inhibitor Bypassing Activity substance but are substantially free of thrombin. Further objects of the invention will be evident from the following description.
2. Description of the Prior Art
There are estimated to be 100,000 cases of congenital hemophilia in the United States. The two predominant types of hemophilia are Hemophilia A and Hemophilia B. A cure for this congenital disease is not available; however, treatment of the disease has been possible by supplying hemophiliacs with active blood coagulation factors by intravenous administration. An early approach was to administer fresh blood or fresh plasma to temporarily correct the defect of the deficient subject. More recently, concentrates containing particular coagulation factors lacking in different hemophiliacs have been isolated from blood plasma. Since these preparations contain the blood coagulation factors in concentrated form, much lower amounts may be used to achieve rapid stoppage of bleeding, and therapy is more specific than with plasma.
One such preparation is called antihemophilic factor (AHF) or Factor VIII for treatment of Hemophilia A. Factor IX (Antihemophilic Factor B) preparations, such as those described in U.S. Pat. No. 3,717,708, are used for treatment of Hemophilia B patients.
Approximately 15 to 25% of Hemophilia A patients have an inhibitor to Factor VIII. Consequently, when Factor VIII preparations are given to these patients, the effect of Factor VIII is negated because of inhibition of its activity. This inhibitor may be removed by plasma exchange of the patient's plasma for that of a healthy donor or for plasma substitutes. However, the complexity of the exchange procedure makes this approach very undesirable. Animal source Factor VIII can be used, but it shortly elicits a foreign protein response which negates its usefulness.
Recently, in U.S. Pat. No. 4,160,025, (hereinafter '025) there was described a new blood-coagulation-promoting preparation from human blood plasma, which contains a blood coagulation effective substance causing a bypassing of the Factor VIII inhibitor. This new substance was termed FEIBA for "Factor VIII Inhibitor Bypassing Activity" substance. It was noted in '025 that certain "activated" prothrombin complex concentrates, containing Factor IX among others, had been used successfully in controlling bleeding of Factor VIII inhibitor patients. The activation of these prothrombin concentrates was probably due to unknown impurities. The FEIBA of '025 was a preparation which safeguarded in a repeatable and deliberate manner a generation of Factor VIII inhibitor bypassing activity. FEIBA was clinically effective and compatible without undesired side effects.
To prepare FEIBA by the method of '025 human plasma containing citrate ions is treated in the absence of free calcium ions with water-insoluble inorganic coagulation-physiologically-surface-active substances, such as silica gel or kaolin, to generate a FEIBA substance. Water insoluble substances are separated from the FEIBA-containing material, which is then treated with a basic ion exchanger, such as a diethylaminoethyl-group-containing high molecular weight substance, to adsorb the FEIBA substance thereon together with coagulation Factors II, VII, IX, and X. The adsorbed material is eluted and concentrated. The new substance with FEIB-activity is a protein with a higher molecular weight (100,000) than that of unactivated Factors II, VII, IX, and X (70,000) and contains some thrombin.
It is known that calcium ions in conjunction with other materials such as phospholipids and activated Factor X assist in the activation of Bovine Factor VII (Radcliffe et al, The Journal of Biological Chemistry, 1975, Vol. 250, No. 2, pp. 388-395, and Radcliffe et al, ibid., 1976, Vol. 251, No. 16, pp. 4797-4802). Further, it is well-known that the action of calcium ions on a mixture of the above coagulation Factors produces substantial amounts of thrombin, which is an undesirable substance when present in materials to be infused into humans. Thus, those skilled in the art have not considered and would not consider the possibility of generating a FEIBA substance by using calcium ions either alone or in conjunction with other agents (e.g. '025).
Currently, there is a Factor VIII Inhibitor Bypassing Activity substance or anti-inhibitor coagulant complex marketed by Hyland Laboratories (Costa Mesa, Calif.) under the name AUTOPLEX.RTM.. The FEIBA:thrombin ratio of this material is about 10:1, FEIBA:Factor II is about 10:1, FEIBA:Factor VII is about 2:9, FEIBA:Factor IX is about 1:2, and FEIBA:Factor X is about 5:1. (The above sample was analyzed according to the assays outlined hereinbelow in the Examples section).